Machine-switching telephone-exchange system.



A. B. SPERRY.

MACHINE SWHCHING TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNEG, IBIS Patented Feb. 18 1919.

UNITED STATES NT OFFICE,

ARTHUR SPERRY, OF NEW YQRK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, 0F NEW YORK, N. Y., A OORPORATIGN 015 NEW YORK.

MACHINE-SWITCHING- TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Eatent.

Patented Feb, 18, 1919.

Application filed June 6, 1918. Serial No. 238,482.

To all whom it may concern:

Be it known that I, ARTHUR B. SPERRY, a citizen of the United States, residing at New York, in the county of New York, State of New York, have invented certain new and useful Improvements in Machine-Switching Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to machine switching telephone exchange systems.

The object of this invention is the provision of improved means whereby a pair of brush sets, which are provided as terminals of the same trunk line, and are carried on the same movable switch element, may simultaneously hunt for a desired line in two groups of line terminals, the set which first engages a desired line being maintained in contact therewith and-being also connected with the trunk line, the other set of brushes being maintained disconnected from the trunk line.

In the present embodiment of the invention, the line terminals are arranged in the switch in two groups, and a pair of brush,

' sets is provided on a common shaft, one set for each group. When a desired line is selected by either brush set the switch is stopped on such line. If the selected line is in one group, a brush switching magnet operates .upon the selection of the line and shifts the trunk line into connection with the set of brushes which has been connected to the selected line. If on the other hand the selected line is in the other group, the brush switching magnet is shunted and the trunk is left connected to the brush set with which it is normally associated, which is the set then in contact with the selected line.

Referring to the drawing, which diagrammatically illustrates one embodiment of the invention, A represents a calling subscribers substation, and B a called subscribers sub station. The line conductors a, b, from substation A. terminate in multiples 1, 2 of a group of automatic finder switches F, the number of finders depending upon the traffic. Multiples i, 5 belong to a line in another group served .by the same finder F. Sub-- station A is also provided with multiple 3, and the line in the other group with a similar multi le 6. The finder F has two sets of brushes 5 and D, brush-set C consisting of wipers 7, 8, 9, and the brush set D consisting of wipers 10, 11, 12. Both of these sets of wipers are mounted to rotate together upon the same shaft (not shown), which is driven by a self-interrupting motor magnet 13. The trunk line talking conductors 14c and 15 0 to which both these sets of brushes belong, terminate in armatures 54, 55 of a switching relay 16 which when energized extends these conductors-t0 the talking brushes 17 and 18 and test brush 19 9f a first selector F S.

The invention will be most readily understood by a detailed description of the operation of the system.

Upon the removal of the receiver at sub station -A, line relay 20 becomes energized, and at its outer armature removes ground from the test multiples 3 of this line in the finders in which it appears, thus rendering the line calling. The line relay 20 at its inner armature closes a circuit for a starting relay 21 as follows: ground, inner armature and front contact of relay 20, starting conductor 22, normal contact 23 of relay &8, conductor 26, relay 21, to free pole of battery. Relay 21 thereupon operates, locking itself to ground over the following circuit as pole of battery, relay 21, its armature 27 and front contacts, conductor '30, armature and back contact of relay 37, conductor 52, armature 2: and back contact of relay 33 to ground. A circuit in parallel with that just traced is also closed by relay 21 to operate the motor magnet 13 of the line finder. This circuit is as follows: free pole of battery. slow relay 34, motor magnet 13, its armature and back contact, conductor 35, armature 27 and right-hand front contact of relay 21, conductor 36, to ground at thearrnaturc 32 and back contact of relay 33 over the path previously traced. The motor magnet 13, by interrupting its own circuit, advances the brush sets C and I) over the calling line multiples in the Well-known manner.

During this movement, the upper winding of a differentially wound stop relay 37 is connected over the armature 58 and front contact of relay 21 to the finder test brush 9, and the lower winding of this differential relay is simultaneously connected-over the armature 57 and front contact of starting relay 21 to finder test brush 12. The circuit conditions are such that this relay balanced and does not operate as long as these test brushes encounter test multiples of non-calling linesconnected directly to ground at the outer armatures and back contacts or the line relays of such lines. When, as in the case assumed, however, the test brush 9 encounters the test multiple 3 which belongs to the calling substation A, and from which ground was removed by the operation of the line relay 20, the diflerential relay 37 becomes unbalanced and operates. In attracting its upper armature, it opens the circuit of motor magnet 13, thus stop.

ping the switch with the brushes 7, 8 and 9 in contact with thevmultiples 1, 2 and 3 of the calling line A. When the starting relay 21 operated upon the initiation o the call, it grounded conductor 31 connected to the lower winding of relay 33. At the same time, however, it connected ground from a grounded test multiple 6 over test brush 12, and conductor 39 in shunt of the effective lower winding of the relay 33. Thus, the relay 33 is shunted and does not operate and the talking brushes 7 and 8 are left connected over the armatures 51 and 41 of the brush switching relay 33 to the trunk conduct-ors 14 and 15.

Assume on the other hand that the call originates in the line represented by multiples 1, 5, 6, wiped over by brush set D. In that event the initiation of the call removes ground from test multiple 6 and starts the finder seeking for the line, as described. 'When the test brush 12 of brush set D encounters this multiple 6, the switch stops, due to the relay 37 operating, but since no shunt path about the lower effective winding of relay 33 exists, an operating circuit for this relay is closed over both windings in series to ground at the armature 35 and front contact of relay 21. Relay 33, in attracting its armatures 51 and 41, transfers the trunk conductors 14 and 15 to the talking brushes 10, 11 of brush set D,

When the finder is stopped on the calling line in either case, that is, whether the callingline is in one group or the other, the relay 37 in operating, opens the locking circuit of starting relay 21 as well as the stepping circuit. The relay '34 is, however, slow to release its armature and consequently an impulse passes from the retracted grounded armature 35 of relay 21 and its back contact, conductor 43, armature and front contact of slow relay 34, switching relay 16, to the free pole of battery. Relay 16 thereu on oper ates and connects the talking con uctors 14 and 15 of the trunk line to the talking brushes of first selector circuit FS. A relay at this selector thereupon immediately operates over the calling line circuit to ground the third wire 38, which ground is applied to has had time to release its armature. Thus the switching relay 16 is initially operated this conductor before relay 34 when relay 21 releases and locks itself up to the grounded test wire 38. The ground on the conductor 38 is transmit-ted to the cutoff relay 50 of substation A over a circuit including conductor 60, armature and back contact of brush switching magnet 33 if the call is from station A, conductors 61, 62, brush 9, multiple 3, spring 63 and contact 64 of relay 50, conductor 65, outer armature of relay 20 and its front contact, conductor 66, cutoff relay to free pole of battery. This circuit operates the relay 50 to out off the line relay 20. Brush 9, being grounded from conductor 38 during the existence of the connection, thus renders the line A non-calling in the other finders in which it appears after it has been extended as described. The line relay 20, in deenergizing, releases relay 21 which opens the circuit which origina ly energized the brush switching magnet 33, which operated as described in case the call came from station A,- but this magnet is slow to release and before it retracts its armatures, a holding circuit is provided for it over its armature 78, conductor 7 7 and the attracted armature 7 6 of switching relay 16. If the call had come in from a line in the other group, the armature 415 of relay 33 would be attracted, and the ground on conductor 38 would he applied to brush 12, and thence to the multiple 6 of such line and the cutoff relay thereof to accomplish similar functions.

Switching relay 16, in attracting its armature 4:6, operates relay 18, which advances the starter wire 22 to starting conductor 40 leading to the starting relay 21 of the next idle iinder in a well-known manner.

The first selector FS and succeeding switches, which may be of any well-known type, may then he set by the calling subscriber at substation A by means of his sender S, whereby the call is extended to the multiples 41, 4:2 and 43 of the called substation B, but since as this part of the system has nothing to do with the present invention and may be of any well-known type, it is not shown in detail. The restoration of the apparatus is brought about by the removal of ground from the conductors 38, due to the release of the connector when the parties to the connection replace their receivers.

Since the spring 63 of the cutoff relay 50 makes contact at '64 before breaking contact with the armature 71, a resistance is provided to prevent the cutoff relay from again operating from the circuit to ground at the outer armature of the line relay 20 after the cutoff relay is once denergized when the connection is disestablished due to the removal of ground from the third conductor 38 leading to the first selector FS. This resistance is of such a value that although the cutofi relay will not operate in series with it, it will, however, hold its armatures attracted through this resistance when once energized.

While the invention is shown as embodied in a switching arrangement for extending calling lines to idle connecting circuits, it is not to be so limited, but is just as applicable to arrangements for selecting idle trunks.

at is claimed is:

1. In a telephone system, the combination with a switch including a plurality of sets of brushes, series of circuit terminals, one for each set of brushes, a trunk line to which both sets of brushes are individual, a. brush switching magnet, v automatic means for simultaneously moving said brushes over their respective series of contacts, means for stopping said switch when a desired line is reached by either brush set, means for operating said magnet when one brush set engages the terminals of a desired circuit to connect said circuit to said trunk line over said brush set, and means for shunting said magnet when the other brush set engages a desired circuit to connect said circuit to said trunk over said last-mentioned brush set.

2. In a telephone system, the combination with an automatic switch including a pair of brush sets, two rows of circuit terminals, one for each set of brushes, a brush switching magnet, a trunk line to which both sets of brushes are individual, automatic means for simultaneously moving said brushes over their respective rows of contacts, means for stopping said switch when a desired circuit is reached by one brush set and for operating said magnet to shift said set into connection with said trunk line and means for stopping said switch when a desired circuit is reached by the other brush set and for shunting said brush switching magnet to connect said circuit to said trunk over said last-mentioned brush set.

3. In a telephone system, the combination with an automatic finder switch including a pair of sets or". brushes, two calling line groups, two groups of calling line terminals therefor, one for each brush set, a brush switching magnet, a trunk line connected one set of brushes over normal contacts of said magnet, automatic means fer simultaneously moving said brushes over their respective groups, means for stopping said switch when calling line is reached by either brush, means for operating saic ma net when one brush set engages the terminals of a calling line to shift said set into engagement with said trunk line, and means for shunting said magnet when th brush set engages a calling line to ex said line over normal contacts of said switching magnet to said trunk.

4. In a telephone system, the combination with a switch including a pair of test brushes, two rows of circuit terminals for said brushes, means for normally grounding the said terminals and for removing ground from a desired terminal, a stop relay for said switch having two differential windings, and circuits for said windings including saidbrushes and grounded test terminals, whereby when a non-grounded terminal is reached said relay operates to stop the switch thereon.

5. In a telephone system, the combination with a trunk line, a switch including a pair of sets of brushes, each set including a test brush and a pair of talking brushes, rows of circuit terminals one for each brush arranged in two groups, means for normally grounding the test terminals of both groups and for removing ground from a desired terminal, a stop relay for said switch having two differential windings, circuits for said windings including said test brushes and grounded test terminals, whereby when a non-grounded terminal is reached said relay operates to stop the switch, a brush switch'ng magnet, and means for operating said magnet when one brush set engages the terminals of a desired circuit to shift said set into connection with said trunk line, the magnet remaining inert when the other set engages a desiredcircuit to extend said circuit over said set to said trunk.

6. Ina telephone system, the combination with a switch comprising a pair of sets of brushes each including a test brush (9, 12) and talking brushes (7, 8 and 11, 12, respectively), two groups of normally grounded test circuit terminals (3, 6), a trunk line, means for removing ground from a desired test terminal in either group, means for stepping the switch when a non-grounded test terminal is reached by either test brush, a brush switching magnet, a shunt circuit therefor including test brush (12) and closed long as said brush encounters grounded test terminals (6), whereby when a non-grounded calling test terminal 3 reached, the trunk remains connected to hes (7, 8) and when test brush. ies a calling non-grounded termithe non-existence of the shunt said magnet to operate to shift the re to talking brushes 10, 11),

css whereof I hereunto subscribe l 1 r a 1 "40 lily nus LSb day or tune, a. i). isle. 

